1. Technical Field
The present invention relates to a belt positioning system and a multi-roller assembly and image forming apparatus employing the same, and more particularly, to a system for positioning a movable belt entrained about a plurality of rollers, and a multi-roller belt support assembly and an image forming apparatus employing the belt positioning system.
2. Background Art
Image forming apparatuses employ various types of movable imaging belts, such as an intermediate transfer belt, a media conveyance belt, and a fixing belt, each of which is entrained about a plurality of generally parallel rollers for moving in a trans-axial direction perpendicular to an axial direction in which the rollers extend parallel to each other.
One problem associated with a multi-roller belt support assembly is that the movable belt occasionally walks or moves laterally in the axial direction due to a lack of parallel alignment between the belt support rollers, which results, for example, from wear and tear of equipment used to rotate the belt support rollers. Such lateral displacement of the belt, if not corrected, would cause breakage or failure of the imaging process where the belt reaches the axial end of the roller and eventually slips off the belt support assembly.
To address this problem, several techniques have been proposed which employ a positioning flange connected to an axial end of the belt support roller to prevent lateral displacement of the belt. For example, a known belt driver system employs an annular positioning flange disposed around the roller end in combination with a guide wheel disposed inward from the flange in the axial direction to contact an edge or near-edge portion of the belt to restrict lateral movement of the belt.
The inventors have recognized that one problem encountered when using a movable belt entrained about a flanged roller is that the belt is subjected to excessive load where the flange strikes or otherwise interferes with an adjoining edge of the belt, resulting in cracks or other defects propagating from the edge portion of the belt, particularly where the belt moves in the trans-axial direction with its edge pressing against the positioning flange in the axial direction.